Signaling system



Nov. 1,' 1927.v A v 1,647,760

c. G. voN ZAsTRow SIGNALING SYSTEM Filed MT! 12, 1.92.5

E. @zu S.

Patented Nov. 1, 1927. Y Y' i l l e nnirsnsrarasrarsur OFFICE..

CURTIS G. VON ZASTROW, OF CHATHAM, NEVI JERSEY7 ASSWIGNOR, BY MESNE ASSIGN- MENTS, TO WESTERN ELECTRIG COMPANY, INCQRPORATED, A CORORATION O'F NEW YORK. f

SIGNALNG SYSTEIM.

Application filed May 12, 1925. Serial No. 29,689.

rlhis invention relates to signaling sysin opposite directions ivill not alleot the tems and more particularly to improvements proper functioning thereof. in signaling over transmission lines with Another object of the invention is the 50 high frequency alternating current Within provision of such a signal suspension means the voie@ range, i that functions equally Well in systems Where ln toll line equipments for veatending the fundamental frequencies for the signals connections between exchanges Where high Ain opposite directions are of quite different frequency alternating curignt Within the frequency. y voice rai used for the ecn'ipos ions of To attain these and other objects there is 'the various signals for dialing and other provided in accordance with one feature of control purposes, it is often rable to the invention7'a relay arrangement whereby suspend the transmission of signals in one a signal responsive' circuit at one station, by direction ktempruarily Vor permanently, y as means of which the transmission of signals 00 the case may be, for the transmission of from this stati-on is suspended, is made re l5 signals in the opposite direction over a sgonsive to incoming signals only during the transmission line. In niej/*stem of this sort Vinterval of no current flow which interval and in particular in systems where the high forms Apart of the transmission of signals frequency used for all of the ls is the from this station. Y e5 same; asrfor example7 in such systems as Anotherl feature of this invention resides are described in'Y Patent 5o. 1,5737991, in the provision of a circuit arrangement granted to l). l. lfurphy, February 28,l whereby the said signal responsive 'circuit 1925, it of particular importance that the is cut Off from or made unresponsive to sigapparatus usedfor signal suspension funcnals outgoing from the station of `which it To tions with accuracy even though the fundaforms a part. y I mental frequences employed for the By these arrannementsj it is readily seen nals in oaposite directions are not exactly that it is imn'iaterial Whether or not the the same. For examole it might yliamcii same fundamental frequencyy is employed and it is indeed, not a Ways possible to adfor the signals in opposite directions as ab- 7 just these frequencies to the desired samesolutely no interference between such signals "0 ness, and consequently, when vsignals from can occur due to the fact that signals in opone end of the line are in proi *ess of'being posite directions can only be transmitted transmitted and the signals from the other and received alternately. end of the line are applied for purposes of The invention has been illustrated in the S0 suspending the first mentioned sic'nals, so accompanying drawing asapplied to a toll call-ed beats or temporary Waves of a greater transmission line Which shows at the outor smaller magnitude may be formed that going end means for transmitting and remay be of such nature and frequency of oc* ceiving4 various combinations `of high frecurrence to cause disturbances to be set quency alternating current impulses While up in the receiving apparatus that Will inthe Yincoming end is similarly equipped and terfere ivith the functioning thereof to the also shoivs the circuit means arranged in extent of preventing the desired'suspension accordance With this invention whereby sigof signals to take place. n nals outgoing from this end are suspended It is an object of this invention to proby signals incoming` thereto. vide, for systems of the above type, an im- Referring now to the drawing, this toll proved signal suspension means so arranged line, as illustrated, may take the place of that commercial variations in the common the toll line in a systeml such as that fully LiL fundamental frequency used forv the signals described in the above mentioned patent granted to l?. B. Murphy. No portions of this system have been illustrated as it forms no part of this invention and in the following description only certain features of such a system will be referred to as have a direct bearing on the functioning of the invention as employed in this type of toll line. lVherever, therefore, reference is made in the following description to such a system, it is understood that for further information of possible interest, reference may be made to the text of tie above mentioned patent.

Assuming then, for example, that a connection over this toll line is desired, the operations taking place in the toll line circuit will be as follows:

rlhe immediate result of a toll operator plugging in at jack 1 will be the operation of relay 2 in an obvious manner over the sleeve circuit to ground through the two windings of vthis relay in series. rllhe operation of relay 2 causes current from a 1000 cycle alternating current source interrupted at a forty cycle rate to be transmitted over the toll line to the inward end thereof. rl `he circuit path at the outward end of the toll line for this signal is as follows: from the 1000 cycle source interrupted at the forty cycle rate through the lower and upperinner armatures and back contacts of relay 3, the lower-inner and upper-inner armatures and front contacts of relay `2 to the talking conductors of the toll line through the upper armature and lower-inner armature and baclr contacts of relay et to the toll line towards the inward end thereof. The operation of relay 2 also closes a shunting circuit for relay 5 at its lower-outer armature and front contact to ground causing this relay 5, which is slow to release, to close an obvious energizing circuit for relay 3 which in operating opens rthe circuit for the signal from the 1000 cycle source interrupted at the forty cycle rate. The period of application of this signal to the line is therefore very short and governed by the slow to -release characteristic ofv relay 5. l'llhis signal besides being transmitted out over the toll line `is also transmitted through the receiving and amplifying circuit 50 which is in every detail the same as that shown in the Murphy patent. The effect of this signal is that rela-y G alternately operates and releases at the rate of forty times per second and this in turn causes the alternating current responsive relay 7 to be operated through circuits alternately charged and discharged in a manner believed to'be obvious, as this relay is particularly designed to respond to current impulses of this rate. The operation of relay 7 closes a shunt circuit to ground at its armature and front contact for the slow to release relay 8 which, in releasing, closes a circuit for the energization of relay '9 as follows: battery, winding of relay 9, lower armature and baclr contact of relay 10, armature and back contact of relay 8 to ground. The operation of relay 9 closes a circuit for relay 10 to ground at the armarelays, the armature and front'contaet of relay 9 to groundat the armature and front contact of relay 11. The purpose of the operation of these two relays will become apparent as the description proceeds.

i'he immediate effect of the signal from the 1000 cycle source interrupted atthe forty cycle rate at the inward end of the toll line will be as follows: 1t will be noted that this signal will pass through a receiving circuit 100 identical to the receiving set 50 and there cause the alternate operation and release of relay 101 at forty times per second. This action on the part of relay 101 results in the operation of the alternating current relay 102 which is similar to relay 7 in the receiving circuit 50, in that it responds only to alternating current impulses vreceived at this rate. The operation of relay 102 kcloses a shunt circuit for the slow to release relay 103 which in releasing closes an energizing circuit for relay 104 as follows: battery, vfinding of relay 104C, lowerfouter armature y and hack contact of relay 111, armature and back contact of relay 103 to ground. lThis causes the operation of relay 104: which closes an obvious energizing circuit for lamp 106 and a locking circuit for itself through itsV lower armature and front contact to ground at the lower inner armature and back contact of relay 107.

The lighting of lamp 106 indicates to the inward operator that this particular toll line has been selected by the toll operator for the extension of a connection to a subscribers line, the number' of which been given the inward operator through the usual call wire as is well known in the art. r1`he inward operator will therefore insert plug 10S in the desired subscribeids jack and relay 107 will thereby be operated and cause the release of relay 10a and the extinguishing of lamp 10G as it will be noted that at this time the alternating current signal from the 1000 cycle source interrupted at the forty cycle rate will have been removed from the toll line and consequently the relays energized through the receiving circuit 100 released.

As is well known in the art, the connection of plug 108 to a subscribers line will bridge lll 'trty tin'ies per second.

troni the 1000 cycle Ysource repeated through Y the tip and ring leads through a battery loop so that relay 109 connected through the retardation coil 110 across the tip and ring conductors ot the toll' line will now operate. The operation of relay 109 closes an obvious energizing circuit tor relay 1111. The operation ot relay 111 closes circuit for relay 113 troni battery through the upper winding ot relay 113, upper inner armature and iront contact ot' relay 111 through the interrupter 114 to ground lnterrupter 1111 is designed to interrupt this circuit at forty nes per second thus causing relay 113 to operate and release at this rate. The circuit iior the lower winding of relay113 through to the upper outer armature and iront and hack contactsof relay 111-is for the purpose ot securing a niore positive ac# tion oi'vv relay 113 asis well known in the art. The operations oi relay 113 cause signals troni the 1000 cycle' alternating current source to he transmitted to the toll line at That is, current the repeating coil 11e and connected through the inner lower armature and 'liront contact ot' relay 111 to the ring side of theline will he connected through the toll line loop to the tip side oi the line through the armature and iront Contact of relay 113 to ground at a ior y cycle rate. These ysignals ot 1000 cycle current will now he received at the out'ard end through the receiving circuit 50 to cause the operation ofrelays 6 andi and the release ot' relayv 8 as hereinloeifore described, and as relay 10 is now operated, the ground applied at the armature and back contact of relay 8 will he connected through the lower armature and trontcontact ofrelay 10, to the middle point of the two wind- .ings oiif relay 2 and thus shunt the upper high resistance winding ot this relay causing an increase in the `sleeve current sui-` cient to light the supervisory lamp at the toll operators cord circuit as is well known in the art. The lighting ot this lainp indicates to the toll operator that the inward operator has extended the connection to the wanted subscriber-s line and the ringing ot the subscrilcei"s line may be begun.

The toll operator now applies current to the tip and ring conductors of the toll line in the usual manner to cause the operation of relay 13. The operation oi relay 13 closes an olnfious circuit it'or relay elr which, in

operating, closes at its upper and lower inner armatures and front contacts a circuit to the toll lineV for current troni 1000v cycle source which is connected to vthe uppeiaiid lower armatures and back contact-s of relay 111. This signal is oi short duration as relay 11 opens the energizing circuit tor relay 15 which is slow to release hut which in releasing closes an energizing circuit for rela-y 14 which in turn opens the circuit troni the Vis operated.

.1000 cycle source. The operation oi relay lrey at the toll'operators position will loe a short signal from the 1000 cyclesource'follow-ed by a prolonged signal from the 1000 rate. The purpose'oi` the-iirst signal is to suspend the transmission troni the inward end of current from the 1000 cycle source interrupted at the toi-ty cycle rate and the purpose oi4I thesecond signal is to cause ringing current' to he transmitted troni the toll line to the subscriloers line. The effect of this first signal willl now loe described. v As the relay 113'is now operating andreleasing at the forty cycle rate it should he noticed that on every release of relay 113 a circuit is completed at its armature and back contact for vthe toll line to the receiving circuit 100 and therefore the signal iiroin 1000 cycle source incoming over lthe toll line will he received at a receiving circuit 100 in the torni ot'a signal of1000 cycle current interrupted at arrorty cycle rate. signal will he received while relay 113is released and the signal outgoing from this end will loe transmitted while the relay 113 This-signal incoming to the receiving circuit 100 will therefore cause the operation of relays 101 and 102 and the release of relay 103. and as relay 111 is now operated, acircuit will he closed for relay l115` as follows: battery, winding of relay `115, lower outer armature and liront contact of relay 111, armature and hach contactofrelay 103 to ground. The operation of relay 115 closes a'circuit for relay 110 through its armature and front contact, lower outer armature and front contact of relay 107 and the inalre-betore-breal con'- tacts ot relay 117 to ground although relay 116 will not operate as long as this circuit is shunted by the ground at the relay 103. However, when the ktirst signal from the outgoing end ceases, relay 103 will again hec-oine energized andv relay 116 will operate and lock in series with relay 115 to the ground at the nialre-hefore-hreal contacts of relay 117. The operation oi relay 116 now opens the circuit for relay 111 which, in releasing, removes the energizing circuit through the interrupter 114C for the relay 113 and these two relays 111 and 113 in releasingI discontinue the application of current ironi the 1000 cycle source interrupted at the fortycycle rate on the toll line. When now the signall troni the 1000 cycle source interrupted at the twenty cycle rate vis apcycle source interrupted at the twenty cycle I That is, this y plied a circuit is provided therefor through the armature and back contact ot relay 113 to the yreceiving circuit 100. The receiving circuit 100 responds in the saine manner as before to operate relay 101 but in this case the alternating current relay 118 is operated in place ot' relay 102 as this relay is designed to respond only to alternating current impulses received at the rate of twenty per second. The operation of relay 118 closes a shunt circuit for the energizing circuit ot relay 119 which in releasing closes an obvious circuit for relay 117. The operation of relay 117 opens with its lower outer armature the makebetorebreak contacts oft the locking circuit for relays 115 and 116 which are now released. Relay 111 can not however be again energized as the circuit tor relay 109 is broken at the upper and lower inner armatures and back contacts of relay 117. The operation of relay 117 now applies the usual ringing current to the tip and ring of the toll line at the upper and lower inner armatures and 'front contacts in the usual manner to ring the wanted subscribers line.

Then the toll operator ceases to ring the wanted subscriber, relays 13, 4 and 14 will be released and relay 15 reenergized and consequently the application of current from the 1000 cycle source interrupted at the twenty cycle rate will be discontinued and relays 101 and 118 will be released while relay 119 will be again energized and relay 117 released and the ringing current disconnected from the subscribers line. The release otrelay 117 reestablishes the circuit tor relay 109 and consequently relays 111 and 113 will be again operated in the manner hereinbetore described to again apply current troni the 1000 cycle source interrupted at the forty cycle rate to the outward end of the toll line and the effect ot the reapplication of this signal will be the same as hereinbeiiore mentioned, namely, that 'the resistance ot' the sleeve circuit will be decreased and cause the lamp in toll operators cord circuit to he lighted to indicate to the toll operator that the wanted subscriber has not yet answered.

1t will be seen that in this instance the application or' signals from the inward end may be temporarily suspended through the application of signals troni the outward end. On the other hand, in case the wanted subscriber answers during the ringing, relay 109 will not operate on the release of relay 117 and consequently relays 111 and 113 will remain in normal position and permanently stop the application of current from the 1000 cycle source interrupted at the forty cycle rate. The etect of this in the outward end and. in the toll operators cord circuit will of course be that the supervisory lamp will remain extinguished after the applicationA of ringing current ceases as anfindication to the toll operator that the subscriber has answered. The connection through the toll line is now completed from one end to the other and conversation may take place.

When the conversation has ended and the wanted subscriber hangs up his receiver, relay 109 will again be energized causing the operation of relays 111 and 113 and the reapplication of current from the 1000 cycle source interrupted at the forty cycle rate to the outward end of the trunk circuit. The effect ofV this at the toll operator-s position will be that the supervisory lamp will again be lighted this time as a disconnect signal and the toll operator will then remove her plug troni jacl 1 causing the release ot relay` 2. The release of relay 2 in turn causes the reoperation of relay and the release of relay 3 and as relay 10 is in operated condition a circuit or relay 4 will be closed at upper armature and front contact of relay from the ground at the upper outer armature and back contact ot relay 2.r The Operationy of relay 4 closes the circuit to the line from the 1000 cycle source which is connected through the armatures and back contacts of relay 14. The operation of relay 4 also causes the release ot the slow to release relay so that this signal of 1000 cycle current will only be transmitted to the line for a short interval. It will be noted that on the release ot relay 15 a circuit is closed for relay 16 that may be trac-ed as follows: loattery winding of relay 16, lower armature and hack contact of relay 15, upper outer armature and back contact ot relay 3, upper armature and front contact of relay 107 upper and outer armature and hack contact otI relay 2 to ground so that on the operation of relay 14, on the release o' relay 15, which is slow to operate as compared with relay 16, current from the 1000 cycle source interrupted at the forty cycle rate will be supplied vto the toll line through the armatures and front contacts ot relays 16 and 14. rthis signal of 1000 cycle current interrupted at the forty cycle rate will however also be very short as the operation ot' relay 16 opens the energizing circuit for relay 11, which, being slow to release, permits relays 9 and 10 to be held up rfor the period during which the current from the 1000 cycle source interrupted at the forty cycle rat-e is to be applied to the toll line. But when relay 11 releases the locking circuit for relays 9 and 10 will loe opened and these two relays released and on the release of relay 10 the circuit for relays 4 and 16 is opened and the release of relay 4 closes the circuit for relay 15 which in turn opens the circuit of relay 14, while the release of relay 16 again closes the energizing circuit for relay 11 and all the relays in the outward end ot this toll line are therefore now returned to their normal position.

The effect of these short signals of 1000 cycle current followed by 1000 cycle current interiaipted at the forty cycle rate at the inward end will be similar to that produced when the toll line was lirst taken for use,

115 and when this impulse ceases, relay 116 will operate in seri-es with 115 as hereinbefore described. The operation of relay 116 opens the circuit for relays 111 and 113 so that the application to the outward end of the toll line of the `1000 cycl-e current interrupted at 'the forty cycle rate will be discontinued. I/Vhennow the short signal of 1000 cycle current interrupted at the 40 cycle rate is applied to the inward end, relays 101 and 2o 102 will again be energized and relay 103 released but as relay 111 is now released, a circuit will be closed from the contacts of relay 103 for relay 104 which provides a locking circuit for itself to the inner lower armature and front contact of relay107 and also closes the circuit for the lighting of lamp 106 which now serves as a'disconnect signal for the inward operator. The inward operator noticing lamp 106 lightedremoves the plug 108 from the connected line v and relays 107, 104, 115 and 116 respectively release, thus restoring the inward end of the toll line to normal condition.

It is readily seen that in the abovedescribed system arranged in accordance with this invention, the suspension of signals is absolutely positive and that the fundamental frequency used for signals in opposite directions need not be exactly the same as the signals outgoing from the inward end will not in any way interfere with the signals incoming from the outward end, when such signals are applied to the receiving set 100 and consequently no beats will occur in theV signals to cause disturbances in the receiving circuit. When asignal is sent out from the inward end, relay 113 is operated and the 'receiving circuit 100 is disconnected from the line and when rela-y 113 is released there is no signal transmission from the inward end while the receiving circuit 100 is then closed to the line for the reception of tlie signals incoming to this end. It is therefore not absolut-ely essential that the fundamental frequencies used for signals in opposite directions are of the same frequency and any desired frequencies may be used as long as the receiving circuit 100 is tuned to the particular fundamental frequency used for the incoming signals. I-Iowever, it is of considerable advantage to use the same fundamental frequency for the signals transmitted in opposite directions in systems of this type as it will reduce the necessary frequency sources to one at eachy exchange while in cases where different frequencies ar-e employed, itis necessary toV maintain a number ofr different frequency machines at each exchange. g Y

lt should bepomted out that this nivention isnot limited in yits application to systems `of the typevdescribed Vabove but may.

be equally well employed in suc-h systems where signals outgoing from either end of a line are required to be suspended.

That is claimed is:

1. In asignaling system, a line, means for transmitting alternating currents interruptedatcertain rates yover said line in one direction, means for receiving said inter- .rupted alternating currents, a signal responsive to said last means, means associated with said receiving means for transmitting currents of the same character over said line in the otherdirection, and 'means responsive to the reception of currents by and rcsponsiveto said receiving means for interrupting the operation of said associated transmitting means during the period of the said reception.

2. In a signaling system, a line, means for transmitting impulses of high frequency alternating currents within the voice frequency range over said line in one direction, means for discontinuing this transmission of impulses consisting of means responsive to the reception of anv impulse of the same fundamental frequency from the opposite end of the line during the transmission of no impulses of the first mentioned end of the line followed by the reception of impulses of the same fundamental frequency at a certain rate from said opposite end of the line and means for resuming the transmission of impulses from the first mentioned end of the line responsive to the discontinuing of the transmission of said last mentioned impulses.

3. In a signaling system, a line comprising an outward end and an inward end, a source of alternating current at said inward end for transmitting signaling current t` said outward'end, a source of alternating current at said outward end for transmitting signaling current to said inward end, a'recciving circuit at said inward end, a relay at said inward end for alternately effectively connecting said first source of current to said line and for connecting said receiving circuit to said line, andnieans controlled by said receiving circuit responsive to yreception of current from saidsecond source for disconnecting said first source of current from said line.

4L. In a signaling system, a line comprising an outward end and an inward end, a source of alternating current at said inward end for transmitting signaling current to said outward end, a source of alternating current at said outward end for transmitting ES l 1,647,760

signaling current to said inward end, a re ceiving` circuit at said inward end, a relay at said inward yend for Connecting said first source of current to Said line, a secondrelay for alternately rendering said connection eective and for connecting` said receiving circuit to said line, and means controlled by said receiving circuit responsive to current from said source at said outward end for restoring said relays to norma-1 and con- M necting` said receiving circuit to said line.

In witness whereof, l hereunto Subscribe Iny narne this 7 day of May, A. D.. 1925.

CURTIS G. VON ZASTROW. Y 

